1. Field of the Invention
This invention relates to an apparatus and a method for cutting, within a shielding confinement, the irradiated components of a nuclear steam generator to reduce such components to a size to permit their subsequent removal from the containment structure of the generator.
2. Description of the Prior Art
The general method of retubing a vertically oriented nuclear steam generator is described in copending U.S. Patent Application Ser. No. 974,161 of common assignee. This retubing requires removing from the steam generator vessel the U-shaped heat exchanger tube bundle. As this bundle is too large to be removed in one piece from the containment structure through the limited sized equipment hatch and is also irradiated, it is necessary to cut the tube bundle into portions of a size that can be removed. The personnel doing the manual labor must be shielded from the irradiated tubes, and the tubes must also continue to be confined, even after cutting into removable sections, in a shielded structure so that they can be removed from the containment structure for further disposal.
A previous method and apparatus for accomplishing this function is shown and described in copending commonly assigned U.S. Application Ser. No. 901,659 filed May 1, 1978. As described therein, the access port in the cask for the cutting tool remains stationary and substantially open. As a result it would be necessary for the tube bundle and wrapper housed therein to be rotated, relative to the cask, for complete exposure to the cutting tool projecting through the port. Also, the workmen would be exposed to the irradiated tubes and resulting combination gases during the cutting process through the open port.